Calculate months to reach max space

I manage a shared drive that has a space limit threshold. If we go above that threshold then we get charged for use of that space.
I'm able to calculate the projected growth but I can't figure out how to calculate the projected number of months until we would reach that threshold.
Column - Description
A - is the month and day
B - is the current amount of space that is being used
C - percentage of space change from month to month
D - is the max space threshold for the drive
E - how much space is currently available on that drive
F - percentage of space currently available on that drive
G - is the current percentage projected average growth rate for that drive
FORMULA: (1/T)*ln(last/first)
where T= count of data points range
where ln = natural log of the most recent current space entry divided by the first current space entry in the data series
H - projected space based on the previous months data
I - here is my issue. I'm trying to figure out how many months it will take to reach my max threshold in column D. This will be a rolling number that will change from month to month.
*Space is in GB.

I've attached the spreadsheet.

Not very sure if I understand your requirement correctly. Try this formula in Cell I2:

Formula:

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Thanks for your response. What I'm looking for is to calculate how many months it will take to reach max space. The drive is constantly adding more content and it is filling up. My task, on a monthly basis, is to project how many months it will take reach max space. The formula you provided makes this calculation based on the monthly change. I was thinking that it be better to calculate based on average growth rate as this would give a more accurate picture?
I hope this helps.

that's easy, simply replace the cell reference.

Formula:

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Originally Posted by jewelsharma

that's easy, simply replace the cell reference.

Formula:

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Thanks for your help. I'm going to go through the long calculation later to verify the results.